Key zoonoses

Naturally transmitted from animals to humans.

Arthropod-borne bacteria and parasites

Fleas

Endemic typhus/murine typhus/Rickettsia typhi, epidemic typhus/Rickettsia prowazekii, Tunga penetrans
Flies

Sand Fly/Phlebotomus-cutaneous and visceral leishmaniasis, Tsetse Fly-African Sleeping Sickness/ T. brucei), Black Fly/Simulium-Onchocerciasis, Mango Fly/Chrysops-Loa Loa, Bot flies-Myiasis
Mites/Chiggers

Scrub typhus/Orientia tsutsugamushi, Scabies, Hair follicle mite/Demodex
Mosquitos

Malaria/Plasmodium, lymphatic filariasis/e.g. Wuchereria (many ARBO viruses as above)
Reduvid bug

Chagas/T. cruzi
Ticks

Rickettsia (e.g. RMSF/R. rickettsii), African Tick-borne Fever/Rickettsia, Lyme Disease/Borrelia burgdorferi, Relapsing Fever/Borrelia, Babesia, Anaplasma, Ehrlichia

Study Table, by Dr. Sam Palpant.
Underlined organisms are most likely to be seen on exams.

Organism	Clinical	Reservoir	Risks	Micro
Pasteurella multocida	Bite wound infection, cellulitis	Dogs, cats	Animal bites	Bipolar Gram-neg coccobacillus
Capnocytophaga	Bite wound infection, cellulitis, sepsis	Dogs>cats	Animal bite in defic. Immunity/asplenia	Facultative anaerobic Gram-neg rod
Toxoplasma	1˚ mostly asympt, then cysts reactivate, esp. brain in HIV/AIDS	Cats	Cat litter, uncooked meat, pregnancy, decreased immunity	Protozoan parasite, non-motile
Bartonella	Cat-Scratch Fever, lymphadenitis, bacillary angiomatosis in AIDS	Cat bite, scratch or lick open wound	Cat contact, bite, scratch	Gram-neg coccobacillus: Warthin-Starry stain
Francisella tularensis	Skin ulcer, adenitis, pneumonia, sepsis	Rabbits, wild animals, pets, ticks	Farmers, hunters, meat-handlers	Gram-neg coccobacillus
Brucella	Undulant Fever/FUO, septic arthritis, SBE	Cattle, pigs, goats, sheep	Unpasteurized milk, animal abortions	Gram-neg coccobacillus
Yersinia pestis	Bubo, pneumonia	Prairie dogs, rats	Rodent exposure	Bipolar Gram-neg rod
Y. enterocolitica	Gastroenteritis	Pigs	Undercooked pork	Bipolar Gram-neg rod
Chlamydia psittaci	Atypical pneumonia	Psittacine birds	Cleaning bird cages	Elementary body
Coxiella (Q-Fever)	Atypical pneumonia, rare endocarditis	Cattle, sheep, goats	Farmers	Survives as extracellular spore
Leptospira	Sepsis, with hepatic and renal injury	Rodents, cattle, pigs, dogs	Farmers, animal urine in fresh water	Motile spirochete found in urine
Rabies	Encephalitis, “hydrophobia”	Bats, dogs, foxes, raccoons, skunks	Wild animal contact, some unrecognized	PCR test of nuchal skin bx or saliva Bacillus anthracis/Anthrax: Cattle, sheep, goats Campylobacter jejuni: Pets, farms or wild animals Capnocytophaga : Dog bites>cat Leptospira: Cattle, rodents Borrelia burgdorferi/Lyme: Deer, rodents Borrelia spp/Relapsing Fever: Rodents, ticks Mycobacterium marinum: Fish Salmonella: Poultry, pets, farm animals Rickettsia rickettsiae/RMSF: Rodents, ticks Rickettsia typhi/Murine typhus: Rodents 3

* Elementary bodies (EB) and Reticular bodies (RB) are NOT usually seen on Gram-stain.

Other important zoonoses

Image credits

Unless otherwise noted, images are from Adobe Stock.

Table of Contents

Arthropod-borne bacteria and parasites

Other important zoonoses